Those who knew him in school in Port St. Lucie, Florida, suggested that Mateen, who died in a shootout with the police on Sunday after killing 49 people at a gay nightclub in the worst mass shooting in US history, had a tendency for threats and violent outbursts.

He was disciplined at school 31 times from 1992 to 1999, The Journal reported. He was convicted of battery in juvenile court for after getting in a fight with a fellow student. And he was suspended for 48 days from 1999 to 2001.

He cheered in class after the September 11, 2001, terrorist attacks and claimed that Osama bin Laden was his uncle, prompting the school to call his father, according to The Journal’s report.

“We joked that he’d become a terrorist,” Robert Zirkle, who knew Mateen through school in 2001, told The Journal. “And then he did.”